Does a 600# flange need to be tested? 2

[Bigfaz]

New 24" natural gas pipeline in WV, USA.
Inspection had me remove all 600# flanges and weld temporary test heads on prior to hydro of a section of pipeline. Design pressure is 1480psi, material is X65. Hydro pressure was 2400psi due to elevation difference. Inspection said the flanges are tested at manufacture site. I don't agree. I was under the assumption 100% of the pipeline had to be strength tested including the flanges. Please advise, Bigfaz

 

[LHarnell]

In my opinion, the golden welds should be nothing but straight pipe-to-pipe butt weld. No fittings, forgings, etc. The whole thing should be hydrotested except for a bare minimum of golden welds. Mill test is not always a guarantee that it is OK.

 

[BigInch]

Somewhat true, but that's not why post fabrication testing is req'd. The pipe mill test doesn't guarantee the quality of ANY construction joint, nor quality of pipe after shippment and handling.

Learn from the mistakes of others. You don't have time to make them all yourself.

 

[BigInch]

Some furher guidance on the topic

What if an operator is using several lengths of pretested pipe (e.g., 40 foot “joints” or “pups”) that must be welded together for the replacement segment. Are the welds excepted as tie-in joints? (PHMSA uses the term joint to identify the connection, welds or fusions, between lengths of pipe.)

The following interpretation for 2012 discusses this situation.
Interpretation Subpart E 1

October 17, 2012
U.S. Department of Transportation
Pipeline and Hazardous Materials Safety Administration
1200 New Jersey Ave, S.E.
Washington, D.C. 20590

Mr. XXXX
Attorney at Law XXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXX

Dear Mr. Paul:

In a letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA) dated December 8, 2011, you requested an interpretation concerning the requirements in 49 CFR Part 195 for pressure testing a segment of pipeline that has been replaced prior to putting that segment in service. Specifically, you asked whether post-installation pressure testing was required for a pipe replacement project involving multiple joints of pre-tested pipe. You also asked whether PHMSA could provide any relevant enforcement guidance documents on this issue.

Pressure testing a pipeline segment before placing it in service is a core requirement of the Federal pipeline safety regulations. Part 195, Subpart E governs the pressure testing of pipeline used in hazardous liquid service. 49 CFR 195.302(a) states:

(a) except as otherwise provided in this section and in § 195.305(b), no operator may operate a pipeline unless it has been pressure tested under this subpart without leakage. In addition, no operator may return to service a segment of pipeline that has been replaced, relocated, or otherwise changed until it has been pressure tested under this subpart without leakage.

The term “pipeline” is defined in § 195.2 as:

“Pipeline or pipeline system means all parts of a pipeline facility through which a hazardous liquid or carbon dioxide moves in transportation, including, but not limited to, line pipe, valves and other appurtenances connected to line pipe, pumping units, fabricated assemblies associated with pumping units, metering and delivery stations and fabricated assemblies therein, and breakout tanks.”

The term “pipe” is further defined in § 195.2 as:

“Pipe or line pipe means a tube, usually cylindrical, through which a hazardous liquid or carbon dioxide flows from one point to another.”

Under these definitions, the term pipe means that section of pipe through which a hazardous liquid will flow from point-to-point and therefore must be pressure tested from point-to-point. No distinction is made as to the length of pipe or the number of welded joints within the replaced pipe segment. Similarly, under § 195.308, a pipe tie-in segment being installed must be pressure tested either with or without the tie-in welds (which themselves require non-destructive testing). Note that the welds connecting several pipe lengths in a section to be tied-in are not tie-in welds. In general, while PHMSA has not required post-installation pressure testing when a single joint of pre-tested pipe is replaced, operators are subject to the pressure testing requirement anytime more than one pipe joint is being replaced.

Regarding your request for enforcement guidance documents, all available PHMSA enforcement guidance materials are posted on the PHMSA website for public viewing at:

http://wwvv.phmsa.dot.gov/foia/e-reading-room.

Once you visit the website, please click on – “III. Staff Manuals and Instructions” to view the enforcement guidance materials. While PHMSA does not have an enforcement guidance document for 49 CFR Part 195, Subpart E-Pressure Testing, we have enclosed an enforcement guidance document dealing with the pressure testing requirement for natural gas pipeline replacement projects under Part 192. While this enforcement guidance is not applicable to hazardous liquid pipelines, it is illustrative of the manner in which PHMSA applies the pressure testing requirement to pipe replacement projects. In relevant part, it states that “the entire replaced segment must be tested… except the tie-in joints” (and notes that the several pipe lengths are not tie-in joints).

Finally, if you have a scenario where you can demonstrate that conducting a post-installation pressure test on a replacement segment is impracticable, you may contact the PHMSA regional office covering the area and submit a proposed alternative in writing for its consideration such as a proposal to perform an appropriate strength test on the segment prior to installation (which PHMSA may elect to witness).

I hope that this information is helpful to you. If I can be of further assistance, please contact me at XXXXXXXXXXXXX
Sincerely,

John A. Gale
Director, Office of Standards and Rulemaking
U.S. Department of Transportation
Pipeline and Hazardous Materials Safety Administration




you must get smarter than the software you're using.

 

[Duwe6]

Nice post on the Interpretation: Two Golden tie-in welds and that's it.

 

[BigInch]

Ya. A bit short of 500 miles.

you must get smarter than the software you're using.

 

[DekDee]

So just to clarify for my future knowledge,
A single length of pipe may be replaced and the only requirement is NDT of the two "golden" welds.
Anything more than a single length of pipe must be hydrotested.
Is that correct ?

It does seem strange - if I have understood the interpretation above.
If I replace a section of pipeline with two pipe lengths I have to hydro the one weld connecting the two lengths but the two welds either side are just subject to NDT ??
Cheers,
DD

 

[BigInch]

Correct.

People always say, "Well in that case, where you draw the line then?"
Well now you know.

you must get smarter than the software you're using.